The idea would have been laughed out of court only a couple of months ago. Yes, Marks & Spencer was in trouble. And yes, there had been a few vague - and largely improbable - suggestions that it might merge with someone else or be taken over. (One fanciful story that did the rounds at M&S's Baker Street head office was that the company was about to merge with Sainsburys). But the notion that the grand old lady of the high street might fall into the clutches of someone such as Philip Green? That was ridiculous.

Certainly, Green had a brilliant 1999. Backed by money from the Barclay brothers, he bought the sad remains of the Sears empire for just under £550 million, and set about taking the company apart and selling its constituent parts. The upshot was that he managed to recover virtually all of his outlay - and keep the £130m property division. It was a model of how to make money from dismembering a company.

But at the heart of the idea that Green could do something similar with M&S lies a huge misconception. There is the small matter of scale, of course: even with its share price languishing at less than £3, M&S is still worth the thick end of £8 billion, which makes it a very different proposition from Sears. There is also the point that trying to buy M&S would be rather like bidding for the Royal Family or saying the Archers might be taken off the air - we might find the company flawed and sometimes exasperating, but it is still something for which the chattering classes feel an enduring affection.

But much more fundamentally, Green's record as a retailer is pretty chequered. Certainly, he has made money out of buying and selling retailers and parts of them. But dealing in companies is not the same as running them.

Green cannot speak publicly for himself now. For the past six weeks, since he was forced to make a formal Stock Exchange announcement that he was looking at the possibility of bidding for M&S, he has had to keep quiet. But even Green's allies admit that, were M&S to be taken over, no bidder could hope to show a profit simply by breaking up the company. Its assets need to be made to yield a better return, certainly. But they are assets which, even with the chain struggling, are probably worth more under the M&S name than they would be under someone else's. Remember: other retailers scramble to be near an M&S store because it is a magnet for shoppers; take away that magnet, and the value of all retail properties in the area - including the one previously trading as an M&S - will fall.

So any bidder would have to think about how better to run M&S, not how to sell its assets. And running retailers is exactly where Green has struggled in the past. He is thought to have approached people such as Allan Leighton of Asda, Terry Green of Debenhams and Richard North of Bass to help tackle M&S - were he to make a bid. But Green's personal history as a retailer is bound to weigh heavily in the minds of any investor being asked to hand control of M&S to the maverick from Monaco.

First, look at his successes. In 1985, he paid £65,000 for an option to buy a company called Jean Jeannie. After a few months, the option was sold for £3m. He paid Sears £20m for Olympus Sports in 1995. The business was sold on, yielding a profit of £38m. Green did a further deal with Sears, buying nearly 200 Shoe Express outlets, which he sold later at a hefty, but unquantified profit. Most spectacularly came last year's takeover of Sears itself.

But look what has happened when Green has tried to run businesses himself. His very first ventures, set up with his mother, Alma, after Green left Carmel College with no O-levels, were generally flops. One, Cupcraft, went bust in 1982. A clothing importer and wholesaler, Tarbrook, was wound up the following year with debts of more than £230,000. He was a director of a women's clothing manufacturer, Buzzville, which was half-owned by his mother. It went into voluntary liquidation owing more than £100,000. And Green was a director of Joan Collins Jeans, formed in 1981. It went under a year later.

More recently, Green bought the Owen Owen department store group. The latest accounts, for the year to January 1999, suggest exactly the picture one would associate with him: the company did little more than break even at the operating level; but selling off parts of the operation brought a fat surplus. Overall, pre-tax profits were £1.3m.

His fans suggest this is unfair: Olympus was sold on at a profit because its performance improved under Green's control. And Mark One, the clothes retailer he bought after it went bust, is showing like-for-like sales rises of around 20 per cent.

But Green's one stint as head of a quoted company, Amber Day, ended with his being ousted after the company failed to meet a profit forecast. His time there started well enough - he joined in 1988, backed with a loan of £300,000 from Tony Berry of Blue Arrow fame, and using more than £4m of his own. And in 1990 - the year Amber Day moved into discount retailing with the £47m purchase of the What Everyone Wants chain - the company's shares were the market's second-best performer.

But there were complaints that Green was running Amber Day as though it was his private concern rather than a listed company. He was mistrusted by the City establishment, and Green went through five firms of stockbrokers in four years. Despite Green's tireless efforts to talk up Amber Day's prospects, the share price fell by two-thirds and he was pushed out in 1992. He was still only 40.

Green said the experience had taught him to stick to private companies, and keep out of public ones. 'I was badly bitten on the leg,' he said of the Amber Day episode. 'The scars have finally healed, but I will certainly never be tempted into that world again.'

His supporters in the press and in the City felt that he and the company had been the subject of an unpleasant whispering campaign.

Suggestions that all wasn't as it seemed at Amber Day were the work of bear raiders, said Green's backers. Certainly, parts of the press were spattered with bearish stories about the company, although these were more than offset by others which supported its performance.

But one thing was established as fact: What Everyone Wants (WEW) had bought shares in its parent, Amber Day, in breach of the Companies Act. A firm has to ask shareholders' permission before it buys shares in itself and it must disclose any purchases. Amber Day had done neither.

Green's initial explanation was that WEW had bought the shares after Amber Day had first made an approach because it wanted more information on this potential suitor. In fact, WEW continued to buy Amber Day shares after the takeover. Indeed, Companies House documents showed that WEW more than doubled its Amber Day holding after the deal in June 1990.

Green said he was unaware of the shareholding. Interest in the share deals evaporated, and no official action was taken.

In 1997 Green had to fend off the threat of further bad publicity. He was linked with Helene, the collapsed textiles group, the subject of a Department of Trade investigation. The investigators obtained telephone records showing a number of calls in spring 1997 between Helene's offices and Green's numbers. This was no evidence of any business dealings, said Green; it was just that he was friends with Michael Harris, Helene's former chief. Harris is currently the subject of proceedings to disqualify him as a director.

Of course, association with people involved in operations which have proved less than above board is not evidence of wrongdoing. But Green has been unfortunate in his choice of friends. They have included convicted fraudster Roger Levitt and Ted Ball, who headed Landhurst Leasing before it collapsed. Ball was jailed for corruption. In neither case were the convictions anything to do with activities involving Green.

None of these friendships should be held against Green. None disqualifies him from being involved in a venture which might bid for M&S. But it is understood that he acknowledges that any bid vehicle he assembles would have to chaired by someone else. The City would seek the reassurance of a well-known worthy at the helm.

Even then, could Green put together a successful consortium? He would have to assemble the financing. The Barclay brothers, who bankrolled him for the Sears project, have very publicly declared they will not be involved in any assault on M&S. Given the meagre projections for M&S's operating profits, it is hard to see how even the most optimistic of backers would finance an all-cash deal.

An alternative would be an offer which gave M&S shareholders some cash plus a 'stub' of equity, giving them the right to share in any profits from selling off any M&S assets plus a stake in the core business. The perception of how much that core business might be worth, of course, would depend on how much faith investors put in a Green-assembled team.

Meanwhile, the phoney war drags on. Green has tried unsuccessfully to have the Takeover Panel demand a statement from Tesco about whether it is interested in bidding for the chain, or would want to buy any M&S stores if they were for sale. Tesco is remaining silent, but there are strong signs that it has very little interest in M&S. .

M&S would like Green to be forced either to launch a bid or declare he has dropped the idea. It is hampered in what it can say because it is under threat of a potential offer. It is thought unlikely that M&S will be able to force the issue for at least a further week.

Green is apparently keeping the pot boiling by telling friends he thinks he could find the backing for a deal.

But as time drags on, his credibility as a potential bidder is starting to diminish. And if a bid does come, it will be the record of Green the retailer, rather than Green the dealmaker that is scrutinised.